The objective of the research described in this proposal is an understanding of the pathways and mechanisms involved in the formation and modification of retina synaptic arrays. The strategy to be used in attaining this goal is the completion of quantitative descriptions of the development of amacrine and bipolar synaptic arrays in the retinas of certain animals and the use of these descriptions as controls against which to measure the results of various experimental manipulations. Furthermore, the differences and similarities of the descriptions among species will be used to deduce common principles of synaptic organization. Finally, age related changes of the retinal synaptic arrays in senile animals will be explored as a continuation of the developmental process.